SLO County weather forecast: Cooler temperatures expected across the Central Coast

Last week, Paso Robles saw an average high temperature of 103 degrees, while usually, it would be 94 degrees. Closer to the ocean, San Luis Obispo averaged a daily high of 80 degrees, slightly above typical seasonal temperatures. Last week’s above-average temperatures, especially away from the coastline, will cool to average seasonal levels this Sunday as a weak surface low-pressure system (1,010 millibars) develops over Point Conception.

This system will produce gentle to moderate (8 to 18 mph) northwesterly (onshore) winds. Consequently, a persistent marine layer will develop along the immediate coastline (Fogust) with little clearing during the afternoon. Away from the ocean, the low marine clouds will spread inland during the night and morning with areas of fog and pockets of mist and drizzle, clearing by the afternoon.

High temperatures will range from the low-70s in the coastal valleys (San Luis Obispo) and the low-90s in the inland valleys (Paso Robles). The beaches will remain in the low to mid-60s on Sunday. Daily high temperatures will warm to triple-digit levels in the North County and low 80s in the coastal valleys on Monday.

Fresh to strong (19 to 31 mph) north to northwesterly winds will develop along the coastline on Tuesday. These winds will produce primarily clear skies throughout the Central Coast, including the beaches. Temperatures along the beaches all range between the high-60s to the low-70s, except the southerly facing beaches of Cayucos, Avila Beach, and Shell Beach, which will reach the mid to high-70s. The coastal valleys will hit the high-80s and the inland valleys the low-100s.

Gentle to moderate (8 to 18 mph) northwesterly winds are forecast on Wednesday, Thursday, and Friday. Consequently, a persistent marine layer will develop along the immediate coastline (Fogust) with little clearing during the afternoon. Away from the ocean, the low marine clouds will spread inland during the night and morning with areas of fog and pockets of mist and drizzle, clearing by the afternoon. Temperatures will cool throughout the Central Coast.

Monsoonal moisture will stream over the Central Coast Central later this week with variable mid to high-level clouds. This condition may bring rain and thunderstorms to the Sierra Nevada Mountains.

The long-range models are advertising above average temperatures and below-average precipitation for September and October.

Surf report

A 3- to 5-foot northwesterly (295-degree, deep-water) swell (with a 7- to 11-second period) is forecast along the Central Coast on Sunday into Monday morning.

Fresh to strong (19- to 31 mph) northwesterly winds off the Central California coastline will generate a 5- to 7-foot northwesterly (310-degree, deep-water) sea and swell (with a 5- to 8-second period) on Monday afternoon into Tuesday, decreasing to 3- to 5-feet (with a 7- to 11-second period) on Wednesday through Friday.

The longer-range models are advertising low swell conditions for most of next week.

A 1- to 3-foot Southern Hemisphere (210-degree, deep-water) swell (with a 15- to 17-second period) will arrive along our coastline on Tuesday and remain at this level through Thursday.

Seawater temperatures will range between 54 to 57 degrees through Friday.

This day in weather history

1918 - A tornado struck Tyler, MN, killing 36 persons and destroying most of the business section of the town. (David Ludlum)

1983 - The temperature at Fayetteville, NC, soared to 110 degrees to establish a state record.

2020 - The northwesterly (onshore) flow allowed the marine layer to return to the Northern and Central California coastline last night. The temperature at Cal Poly dropped to 63 degrees at 3:54 a.m. this morning, that’s 30 degrees cooler than the same time yesterday. Once again, Paso Robles remained below 100 degrees yesterday due to the extensive and think layer of smoke.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

John Lindsey’s is a longtime meteorologist who lives in Los Osos. Email him at JohnLindseyLosOsos@gmail.com.